Immunodeficiencies & infections

Question 1

Most Primary Immunodeficiencies are single gene defects, what are the 3 domains?

Answer 1

1) Ab deficiency due to defect in B cells
2) Cellular due to T cell defect
3) Innate due to PRRs, phagocytes of complement defect

Question 2

What about a child’s illness would make you suspect an immunodeficiency? [5]

Answer 2

SPURR:

• Severe
• Persistant
• Unusual
• Recurrent
• Runs in family

Question 3

What infections arise from Ab deficiencies? [3]

Answer 3

Recurrent resp bacterial infections [1] incl Pneumococcus & H influenzae [2]

Question 4

What type of infections arise from T cell deficiencies? [3]

Answer 4

Opportunistic infections [1] incl Pneumocytic Jiroveccii pneumonia (PCP) [1] & CMV pneumonia [1]

Question 5

What type of infections would you expect to see in a phagocyte defect? [2]

Answer 5

Staph aureus –> Sepsis, skin inf & deep organ abscesses

Aspergillus –> Lung, bones & brain inf

Question 6

What infections do you see in complement deficiency? [1]

Answer 6

N. Meningitidis (So meningitis)

Question 7

What could you do if you suspect Primary Immunodeficiencies? [3]

Answer 7

Ab? –> Ab tests & measuring immune response to vaccination with common pathogens

T cell? –> Diff WCC & immunophenotyping

Complement? –> Measure complement activation & individual factors

Question 8

Invasive fungal infections e.g. Candida Albicans or Aspergillus Fumigatus are often a presenting symptoms of Primary immunodeficiency. What else would cause one?

Answer 8

• Neutropenia e.g. leukaemia/chemo
• Neonates (immature immunity)
• Broadspec Abx and/or abdo surgery

Question 9

What are the differences between an invasive candida vs aspergillus infection? Think about:
Endogenous/exogenous
Transmission
Blood culture +ve/-ve
Complications

Answer 9

Candida:

• Endogenous
• Get from birth canal/staff’s hands
• +ve blood cultures
• Metastatic Foci

Aspergillus:

• Exogenous
• Get from air/water/environment
• -ve cultures with pulm disease
• Angio-invasive

Question 10

Who tends to get neonatal Candidaemia? [1]

Answer 10

Low BW babies( mainly prems) in their 2nd/3rd wk

Question 11

What do you suspect in a premature neonate with sepsis syndrome, thrombocytopenia & Hyperglycaemia?

Answer 11

Neonatal Candidemia

Clue is the hyperglycaemia, in a bacterial infection that would be low